1. Field
The present disclosure relates generally to nondestructive inspection and in particular to using backscatter x-rays in nondestructive inspection. Still more particularly, the present disclosure relates to detection of objects using backscatter x-rays.
2. Background
Unidentified objects in an aircraft structure are undesirable during operation of the aircraft. Objects may be located within areas of an aircraft that are hard to reach or inaccessible, such as enclosed in a sealed area or within a structural component of the aircraft, for example. Detecting and identifying objects in these hard to reach or inaccessible areas of the aircraft may be difficult and even impossible without disassembly of the aircraft structure.
Nondestructive inspection is a range of analysis techniques used to evaluate properties of an object without causing changes or inconsistencies in the object. The object may be a part, component, system, or some other suitable object. One common technique used for nondestructive inspection is radiographic imaging. Radiographic imaging uses x-ray machines, or some other radioactive source, as a source of photons. Radiographic imaging detects and measures the reaction of photons to the material, component, or system being tested.
X-ray systems detect transmission of photons through an object to form an image. Photons generally interact with objects by either passing through an object, being absorbed by the object, or being scattered from the object. The greater the density of an object, the more photons are either blocked or absorbed rather than passing through. In contrast, when an object is less dense more photons are able to pass through the object as compared to objects that are more dense.
Backscatter x-ray systems detect radiation, or photons, that come back from a target, rather than detecting transmission of photons through a target as with traditional x-ray machines. Backscatter x-ray systems form images based on how photons scatter when encountering an object. Because of this difference, backscatter x-ray systems have potential applications in situations where non-destructive examination is required but only one side is available for examination. One situation where backscatter x-ray systems are useful is in searching containers and vehicles. Some backscatter x-ray systems are able to penetrate up to three centimeters of solid steel, providing search access to sealed or hard to reach areas.
Therefore, it would be advantageous to have a method and apparatus that takes into account one or more of the issues discussed above, as well as possibly other issues.